Leaves cupping/curling and another one is yellow

I'm heaving some problems on these plants. They are already 50days or so.
I've used 2 older leds. Not really happy about those. Like my viparspectra much better.
My previous plants also struggled under these leds. Until they were placed under the viparspectra's R900, then they strived.
I was hoping on the same thing, since i've builded a cob set for this 1x1m tent.
(300w 3500K ). They are now 1week underneath it.

what changed ? The heat, tent is 3°C colder, still 18-23°C.
Humidity on point. 30-60% ( depending on watering), normally about 40-50%
I use very hard tapwater. ( 550ppm)
I ph always at 6-6.2
Recently i learned that i have to let the water sit for 1-2days prior watering to let the chlorine evaporate.
I don't water them often. Since they are in boxes of minimum 25l. ( 2 per box)
The onces affected are in a bigger box(50L). I can look trough them and see if the soil is dry or not.
I must say this time i didn't watered them from beneath. ( since the box is to big).

I sprayed them with PH'ed water + spray mix ( not daily ) And i saw white spots from the hard evaporated water ( chalk )

I gave them once a smal portion of rootstimulator. ( smal small dosage)

These are all the same seeds. (10of them in the tent) (2smallest one in the middle are in small boxes (5l or so)

My soil:

soil based on perlite,silicium
fertilizer based on calcium & magnesium & nutrietns
Dry crap ; 24%
Organic : 20%
PH 4.5-7
EC : 40mS/m
NPK 14-16-18


They all got some low stress training. ( Lots of bending, probably to much)

The one on the left got a led burn a way back , still didn't recover properly.
Also has those wilted leaves


I know the one on the right has a N deficiency ?? ( strange because got the same as others lol)

The canoeing leaves are probably from overdoing bloom nutes and poor humidity

look overwatered maybe? what's your watering schedule - that striping could be magnesium deficiency but not sure. Be careful with very hard water, more than likely contains a lot of calcium carbonate, too much calcium for your plants can lock out other nutes, good luck

Look locked out.

When misting my plants I do it when the lights go out
The hard water spots sound like you need more air movement
I would at this point mix a couple tablespoons of epsom salts in a quart of water and mist them every night for a week and see how they look

So i don't give them nutes.
Only the hard water.
Where the other ones don't get a lock out, those 2 get it ..
I also highered the lights a bit.

+ I did not gave them lots water yet. Only when box is feeling dry and looking dry. ( i can look trough box)